One of the more tedious aspects of development is debugging. Apache logs often provide a lot of useful information about things that have gone wrong, some related to code, some not (honestly, script kiddies, quit trying to access phpmyadmin).
There are many circumstances where you want to present modal views in an iOS app. The one that confronted me was a Login form the first time a user opened the application (and technically, any time thereafter if she never successfully logged in).
Every once in a while, you need to have a web application sit outside the "normal" places expected by Apache. Under Mac OS X (and several flavors of Linux), there are safeguards in place to prevent this.